Telephone system



Sept. 2 1924. 1,506,759

' A. E. LUNDELL TELEPHONE SYSTEM Filed Nov. 1 1919 Sub.

7/1 Men/0K A/ben .5 land? Patented Sept. 2, 1924.

UNETE STATES MET caf ALBEN E. LUNDELL, OF CHICAGO, ILLINOIS, ASSIGNOB TO WESTERN ELECTRIC CO'IvI- f;

PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed November 1, 1919.

To all whom it may concern:

Be it known that I, Annnn E. LUNDELL, a citizen of the United States, residing at Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Tmprovements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to special service systems for telephone exchanges.

In the systems employing so-called manual working, that is, where operators are employed "for answering calls and for establishing connections, certain special service features have been developed, especially in private branch exchange working. One of these features is that termed night service. l-leretotore, such service has been provided by wiring special apparatus into the cord circuits providing night service keys for changing the character of such circuits and keys for changing the character of other circuits in the switchboard. 0n the whole, such 'ght service arrangements have been unsatisfactory, because only so many lines could be provided for as there were central oiiicc t links, and then all calls between the hr cs had to be routed through the central office, thus transferring the duties of the private branch exchange operator to the central ofiice operator.

The object of this invention is to provide a more flexible arrangen'ient whereby such special service may be supplied to a larger number of subscribers and where the duty of switching will not be transferred from one operator to another, but will be performed automatically.

In accordance with this object, means are provided. whereby the trunk lines and certain subscribers lines may be provided with incoming service and this arrangement is not limited by any other arrangements at the exchange.

Also in accordance with this object, means are provided whereby certain subscribers lines may be supplied with outgoing service to the central oflice or to any of the other subscribers lines which are provided with the first-mentioned means.

Broadly, the first-mentioned. means consists in a relay arrangement whereby the lines which may be called may have taps normally disconnected from the said lines Serial No. 334,945.

leading to the multiple banks of simple automatic switches.

Broadly, also, the second-mentioned means consists in a simple automatic switch which may be patched to a line to be temporarily provided with outgoing switches.

Hence, during the slack hours of the day or night, it is only necessary that the lines which are to have outgoing service be source of current is provided which will act to raise the potential of the testing points when the first-mentioned potential is for any reason reduced below a certain level.

In the drawings, l igure 1 is a diagrammatical representation of the circuits employed in carrying out this invention. Fig ures 2 and 3 are schematic details of Figure l and are provided for the purpose of clearly explaining the operation of means for equalizing the potential of the testing points.

The drawingshows, in the upper righthand corner, three'lines, each terminating in a manual su' itchboard. The line 1 is an ordinary s'nbscribers line terminating in a jack 2. The subscriber at substation 1, by removing his receiver -from the book, may cause the lamp 8 to be lighted in a series circuit including the substation loop. The subscriber at substation 4 is provided with a 'jack 5 and may, in the same way, cause the illumination of signal lamp 6. It will be noted that the subscribers loop to the substation t passes through the back contacts of a relay 7, but in every other respect this line is, under normal conditions, the same as that to sub: station 1. A line 8 terminates at a central oflice (not shown) and is there provided with the usual arrangements, that is, a line and cutoff relay, signal lamp, answeringjack and multiple jacks. The trunk line 8 terminates at the manual switchboard in. a jack 9 associated with which is a lamp 10. The central ofiice operator, by plugging into a multiple jack at the central oirlce and ringing over the line will energize the righthand winding of relay 11 in a series circuit including the contacts 01? the jack 9. and the condenser 12. Relay 11, upon energizing, closes a circuit from battery, the left-hand winding of the relay 1]., the contact 13 on the jack 9, the armature and contact of relay 11, the lamp 10 to ground. Calls estab-' lished to the manual switchboard may be answered and connections established in the Well-known manner.

In the upper part of the drawing, near the left-hand end is shown a cord circuit 14 provided at each end with a plug 15 and 16 respectively. This double ended cord is used for patching purposes, as will hereinafter be described.

The lower part of the drawing shows the circuits to an automatic switch having brushes 17, 18, 19, 20, 21 and 22 associated with a terminal bank, numbered as a whole, 23. Each set of terminals in this bank may be connected with a trunk line, such as that subscribers line such as 4, leading to a substation within the exchange. Each subscribers line, such as 4, is pro 'ided with a relay 7 and a pair of taps which, under the influence of relay 7, may be connected to the substation 4. 'Each trunk line, such as 8, is provided with a relay corresponding to 7, here numbered 24, which is instrumental in connecting the pair of taps from the multiple 23 to the trunk line 8.,

Let itbe assumed that the slack hour of the day has been reached and the operator- -wishes to leave the board and at the same time provide service for certain of the subsubscribers who may have occasion to use their telephones. Let it be further assumed that a subscriber at substation 1 will wish to use his telephone during such slack hours to establish connections to the central office over the trunk 8 and to a subscriber atv station 4. The operator thereupon inserts the plug 16 into the jack 2 and the plug 15 into the jack 25. No other arrangements need be made by the operator.

Let it be assumed that the subscriber at substation 1 now wishes to communicate with the subscriber at substation 4. In removinghis receiver from its hook, the subscriber at substation 1 will. energize relay 26 through a circuit extending from battery, left-hand winding of relay 26, contact and outer left-hand armature of relay 27, line 28, relay 29, ring of the jack 25, ring of the plug 15, ring of the plug 16, ring of the jack 2 through the loop of the substation 1, tip of the jack 2, tip of the plug 16, tip of the plug 15, tip of the jack 25, line 30, inner left-hand armature and contact of relay 27, right-hand winding of relay 26 to ground. Relay 26 alone energizes in this circuit and in so doing a circuit is established from ground, brush 22, the contact upon which it normally rests, c0nductor 31, righthand armature and contact of relay 27, armature and front contact of relay 26, winding of relay 32 to battery and ground. Relay 32 energizes in this circuit and through its left-hand armature establishes a' circuit from ground, left-hand armature and contact of relay 32, winding of relay 33 to battery and ground. Relay 33, upon energizing, connects the motor magnet 34 through the winding of relay 35 to the back contact of relay 26.

If the subscriber at substation 1 now manipulates his sender 36, the brushes of the switch 23 will be positioned on the set or terminals associated with the substation 4. Upon each interruption of the line circuit, the relay 26 will be deenergiz'ed and thereupon a circuit will be established from ground, brush 22, the contact upon which brush 22 normally rests, or after the brush 22 has left this contact from ground, the inner left-hand armature and contact of the relay 33 to the conductor 31, the right-hand armature and contact of relay 27, the armature and back contact of relay 26, the winding of relay 35, the front contact and righthand armature of relay 33, the winding of motor magnet34 to battery and grouuc. interruptions of the line circuit will cause this last traced circuit to be established six times and the motor magnet 34 to be energized six times whereupon the brushes 17 to 22' will be placed on the terminals leading to the substation 4. 7 v

Relay 35 serially included in the circuit with the motor magnet 34 being slow to release remains energized during the transmission of this series of impulses. During its energization, a circuit is established from ground, the resistance 36, the front contact and armature of relay-'35, thewinding of relay 37.110 battery and ground. Should the called substation 4 be idle, a connection will now be established from ground, the winding of relay 7 the contact upon which brush 21 now rests, brush 21, the outer lefthand armature and contact of relay 33, the contact and armature of relay 37, the winding of relay 37, to battery and ground where upon the relay '3'? is maintained energized and relay 7 becomes energized. After a short interval, the armature ofrelay 35 is retracted and a circuit is thereupon set up from ground through the winding of relay 7, the outer left-hand armature and contact of relay 33, the contact and armature of relay 37, the armature and back contact of relay 35, both windings of relay 38 to battery and ground. Relay 38 becomes energized through its two windings 111 series. However, as soon as 1t attracts its armatures, its right-hand winding being shunted hand winding of relay 38 and the winding of relay 37 are in multiple and through them current flows through the test brush 21 and the winding of relay 7 to ground.

It will be understood that circuits of the nature of those shown in Figure 1 are used at points distant from a central office. In such cases the source of current is sup-plied over conductors from the central office and since there is more or less resistance in the leads a heavy load at the switching point will reduce the potential of this source of current.

If the potential of the source of current is thus reduced, relay 37, being marginal, will retract its armature and the condition shown in Figure 3 will be established. Here the right-hand winding of relay 38 will no longer be shortcircuited but will be included in a series circuit with the winding of relay 37, whereupon the relative potential at the brush 21 will be raised due to the larger amount of resistance included between it and the source of current. This rise in potential will compensate for the drop in potential of the source of current and thus the potential of the testing points will remain practically constant.

Relay 38, through its energization, connects the wires 39 and 40 to the wires 41 and 42 respectively leading to the brushes 17 and 18 respectively. At the same time, a circuit is established from ground, the contact and inner lefthand armature of relay 33, conductor 31, right-hand armature and contact of relay 27, the armature and front contact of relay 26, conductor 43, the contact and outer right-hand armature of relay 38, brush 19, the terminal upon which it rests. conductor 44, contact and armature of ringing relay 45, back contact and armature of relay 46, winding of relay 47 to battery and ground. Relay 47 in energizing, establishes a ringing circuit for calling the subscriber at substation 4. This circuit may 'be traced from the source of ringing current 48 through the winding of relay 45, the front contact and outer armature of relay 47, the conductor 40, the outer left-hand armature and front contact of relay 38, conductor 42, brush 18, the terminal upon which it rests, the front contact and outer lefthand armature of relay 7 through the loop of the substation 4 and the signal dial thereat. the inner left-hand armature and front contact of relay 7, the terminal upon which brush 17 rests, brush 17, conductor 41, the I front contact and inner left-hand armature of relay 38, conductor 39, inner armature and front contact of relay 47 to ground. The current flowing over this circuit from the source of ringing current 48 is insufficient to energize the relay until the subscriber at substation 4 removes his receiver from its hook. At this time, the'relay 45 energizes, whereupon the circuit for the-energization of relay 47 is now changed to serially include the winding of relay 46. Relay 46, upon energizing, shunts the winding of relay 47 by theconnection to battery at its front contact and right-hand armature and is thereafter held locked in the circuit including brush 19, outer right-hand armature and contact of relay 38 to ground over the circuit heretofore described.

A conversational circuit between substation. 1 and substation 4 is now established, and conversation may proceed, talking battery being furnished from the windings of relay 26. v

Let it be assumed that substation 4 was already involved in a connection such as that just described. In this case, the test brush 21, upon being placed on the terminal connected to the winding of relay 7 would find not ground but a potential somewhat between ground and battery and such potential would. be insufficient to hold the relay operated.

l-lence, as soon as the armature'of relay 35 was retracted from its front contact. relay 37 would become deenergized and there would be no circuit for the energization of relay 38. In this case, a circuit from ground, the front contact and right-hand armature of relay 32 through the left-hand winding of impedance coil 49, the winding of buzzer magnet 50, the armature and back contact of buzzer magnet the right-hand winding of impedance coil 49 to battery would be established. Buzzer magnet 50 be ing provided with an armature and back contact in its own circuit would vibrate its armature and through rapid makes and breaks of the circuit just described would produce a tone which, transmitted over the back contact and outer left-hand armature of relay 38 to condenser 51, the'conductor 28, the outer left-hand armature of relay 27, the winding of relay 26 to battery and ground, would produce, by induction, a tone in the receiver at the substation 1 thereby informing the subscriber at that substation that the called line 4 is busy.

The subscriber at substation 1 would thereupon restore his receiver to its switchhook and through the opening of the loop to his substation, would deenergize relay 26. The armature of relay 26 upon contacting with'its back contact establishes a circuit previously described for'the 'energization of motor magnet 34, whereupon the brushes are stepped to the next set of contacts. In a short time, slow-releasing relay 32 becomes deenergized and in turn, relay 33 becomes deenergized whereupon a circuit is established from ground, the brush 22, the strip 52 upon which the brush 22 contacts in all positions except its normal position, this switch being of the rotary type, from'the strip 52 through the armature and back contact and right-hand armature of relay 33, winding of magnet 34 to battery and ground. Magnet 34 being included now in the selfinterrupting circuit moves the brushes stepby-step until they have returned to their normal position whereupon the switch and the circuits therefor are in the position shown in the drawings. 7

Restoration from an established connection is accomplished in the same manner.

Let it be assumed that the substation 4 is connected to a set of terminals which are more than ten steps from the normal position of the switch, say 15. In this case, the substation 4 might be called through the the number 96. If the subscriber at substation 1 first dialled 9 he would set the brushes of the switch on the ninth set of terminals which would, under these conditions be blank, that is, no multiple wire would beconnected to them. At the end of this series of nine impulses, the circuits of the switch would be as described when a busy line is reached, that is, relay 37 would become deenergized and prevent the. energization of relay 3S. Thereupon the subscriber would dial the digit 6 and the brushes would be advanced six more steps, that is, to the fifteenth set of terminals and to the line number 96, here shown as substation 4.

It will now be assumed that the subscribe at substation 1 wishes toestablish connection to the central office over the trunk S, as indicated on the drawings, but will dial 3, that is he will manipulate his sender 36' to transmit three impulses or rather to interrupt his line three times. In the manner heretofore described, the brushes 17 to 22 inclusive will be placed on the terminals leading to the trunk 8. If the trunk is busy, a perforn'iance heretofore described will be repeated and the busy tone being received by the calling subscriber, he will disconnect and his switch will be restored the central ofiice over-the circuit including the high resistance line relay usually. provided at the central office, but will, however, cause the line relay to-be energized and the calling lamp illuminated. The operator at the central office, plugging into the trunk will, through her cord circuit, supply, an

increased potential whereby the relay 53 will which brush 2O rests, winding of relay 27 to battery and ground. Relay 27, through its left-hand armatures cuts off the relay 26 from the. connectionand at its inner righthand armature removes the ground from the armature of relay 26 whereby, when relay 26 retracts its armature, the motor magnet 34 will not, be again energized. Relay 27 in attracting its outer left-hand armature connects conductor 28 to conductor 40. Relay 54 also through its. left-hand armatures connects the trunk 8 to the terminals upon which brushes 17 and 18 rest and thereupon establishes a conversational circuit between the subscriber at substation 1 and the trunk 8, battery being supplied from the central office for talking purposes. This battery current flmving through the supervisory .relay 29 energizes this relay to establisha circuit from ground, the contact and inner lefthand armature of relay 33, conductor 31, contact and armature ofrelay 29,the winding of relay 32 to battery and ground to hold relay 32 and consequently relay 33 energized during the establishment of this connection.

l/Vhen the conversational period terminatesand either the subscriber at substation 1. hangs up his'receiver or the operator at the central oflice removes herplug from-the trunk S, the relay '29 will be deenergized whereupon relay 32 and in turn, relay 33 become deenergized. The motor magnet 34 is now included in a self-interrupting circuit and the switch will be restored to-its normal position as heretofore described.

It will be seen from the foregoing description thatnight servicemay be supplied to any number of substations and central ofiice trunks as may be required, the only limit being the capacity of the automatic switch. It will also be seen that outgoing night service may be supplied to as many subscribers as there are automatic switches. The only arrangements.which theoperator has-to make upon leaving the board, are to patch substations which are to receive outgoing service to the automatic switches through the agency of jacks, such as 25. A substation may have outgoing service and not incoming service. Again a substation may have incoming service and not have outgoing service or it may have both. Incoming service over a trunk line from the central oflice may be arranged it the central ofiice operator is supplied with a sender in her cord circuit.

hat is claimed is:

1. In a telephone system, lines and trunk lines, manual means for interconnecting said lines and for interconnecting said lines and said trunk lines, automatic switches, multiple terminal banks for said automatic switches, means individual to certain 01'' said lines and said trunk lines for connecting said lines and trunk lines to said multiple terminal banks, means for connecting said switches to certain of said lines, and means responsive to said last lines for operating said switches tooperate said individual means and establish connections to said lines and said trunk lines.

2. In a telephone system, a manual switchboard, a plurality of automatic switches, lines terminating in said manual switchboard, means tor establishing connections through said automatic switches to certain of said lines, said certain lines being normally disconnected from said switches and means for temporarily connecting certain of said lines each to one of said automatic switches whereby said last lines may control said switches to establish connections to said first said certain of said lines.

3. In a telephone system, an automatic switch having a testing contact, a controlling circuit having therein a plurality of electromagnets and a source of current, one of said electromagnets being sensitive to changes in the potential of said source of current and having means responsive thereto to alter the number of said electromagnets to control the potential of said testing contact.

4. In a telephone system, an automatic switch having a testing contact, a controlling circuit having therein a plurality of electromagnets and a source of current, one of said electromagnets being sensitive to changes in the potential of said source of current and having means to control the potential of said testing contact.

In witness whereof, I hereunto subscribe my name this twenty-eighth day of October ALBEN E. LUNDELL. 

